kv 42 perspective transform

#galaxy.py

from kivy.app import App

from kivy.graphics import Line

from kivy.metrics import dp

from kivy.properties import NumericProperty

from kivy.uix.widget import Widget

class Galaxy(Widget):

    def __init__(self, **kwargs):

        super().__init__(**kwargs)

        self.n_vlines = 7

        self.space_vlines = dp(100)

        with self.canvas:

            self.vlines = []

            for i in range(self.n_vlines):

                vline = Line(points=(0,0,0,100))

                self.vlines.append(vline)

    def on_size(self, *args):

        start_x = self.center_x - int(self.n_vlines/2)*self.space_vlines

        for i in range(self.n_vlines):

            x = start_x+self.space_vlines*i

            x1, y1, x2, y2 = x, 0, x, self.height

            x1, y1 = self.perspective_transform(x1, y1)

            x2, y2 = self.perspective_transform(x2, y2)

            self.vlines[i].points = (x1, y1, x2, y2)

    def perspective_transform(self, x, y):

        #return x, y

        tx = (self.height-y)/self.height*(self.center_x-x)

        return self.center_x-tx, 0.8*y

class GalaxyApp(App):

    pass

GalaxyApp().run()

------------------

#galaxy.kv

Galaxy:

    BoxLayout:

        size: root.size

reference:

https://www.youtube.com/watch?v=l8Imtec4ReQ&t=529s